Natsumi Kawaguchi defeated Sara Saito 1-6 7-6 7-6 in the W60 Fukuoka quarter-final on carpet. The upset overturned the form book — Sara Saito came in ranked #241, leading the head-to-head 3–0. Natsumi Kawaguchi claimed a first win over Sara Saito in four meetings, narrowing the head-to-head to 3–1.
| Date | Tournament | Round | Surface | Winner | Score |
|---|---|---|---|---|---|
| 2025-09-25 | W100 Incheon 1 | R16 | hard | Sara Saito | 6-4 6-4 |
| 2024-04-09 | W35 Osaka 1 | R32 | hard | Sara Saito | 6-4 6-1 |
| 2022-09-26 | W25 Nanao | Q16 | carpet | Sara Saito | 3-6 6-3 10-5 |
Averages over each player's completed matches in the selected window (60 vs 97). ATP, WTA & Challenger.
Each player's serve crossed against the other's return, converted to expected hold of serve. Recent completed matches, ATP, WTA & Challenger. About